Kilocalorie of energy

The geometry of the cis-alkylcyclohexanol is favorable for trans elimination since the hydroxyl and the neighboring trans hydrogen are coplanar, but this is not true for the l,i-trans isomer hence the molecular conformation has to flip over, to set the hydroxyl group in the axial position for the trans elimination to occur. This would require a few kilocalories of energy and for frans-lert-butylcyclohexanol it would be more difficult to achieve than for IroMs-methylcyclohexanol. It is, therefore, possible that the trans elimination from a boat conformation, or possibly even an epimerization from the trans to the cis isomer which then undergoes a trans elimination reaction. Such an epimerization was found to occur under conditions of dehydration of certain alcohols over alumina, as will be seen under 1,4-cyclohexanediol. The more facile elimination of the cis-i-tert-butylcyclohexanol system as compared with the trans system in solution was also reported in the literature 63). 

It therefore requires 12.78 kilocalories of energy to heat this particular piece of aluminum. Conversely, if a kilogram of the same metal cooled from 70° to 10°, 12.78 kcal of heat will be released into the environment. 

An exothermic reaction releases 86.5 kJ. How many kilocalories of energy are released ... 

A calorie is a unit of heat energy defined as the amount of energy it takes to raise one gram of water by one degree Celsius. Calories are also often used to describe the energy content of foods. When used for foods, a calorie actually refers to 1,000 calories, or a kilocalorie of energy (which can be rather confusing). 

Calorific Value.—When completely combusted into carbon dioxide, nitric acid, and water, 1 gm. of dry protein yields 6 8 kilocalories of energy. In the organism, however, oxidation of the nitrogen is only carried as far as urea, and for this reason the calorific value of food protein is only 4-1 kilocalories per gram. 

The average daily protein intake of 80-100 gms. provides about 400 kilocalories of energy, leaving a balance of some 2,600 kilocalories to be supplied by the lipides and the carbohydrates. 

The SI Systeme International d Unites) unit of energy is the joule (J) An older unit is the calorie (cal) Most or game chemists still express energy changes in units of kilocalories per mole (1 kcal/mol = 4 184 kJ/mol)... 

Let me tell you how things were in the heady days of the late 1960s, when scientists (like me) and engineers first got their hands on computers. Computers were very large beasts, and they consumed very many kilojoules (kilocalories in those days, or if you are a North American reader) per unit time. If you believe in the law of conservation of energy, you will understand why such machines had a refrigeration plant, where the three resident engineers kept the milk for their coffee. 

The bicycle s energy efficiency superiority extends beyond hninali loconiotion and beyond all other forms of transportation. By com ertmg food into the energy equivalent of gasoline, the kilocalories of food energy needed by a human to pedal a bicycle is only a fraction of that needed to propel planes, trains, and automobiles (see Table 1). 

The basic unit of energy used in accelerator physics is the electron volt (eV), which is the energy acquired by an electron when accelerated through a potential difference of one volt. An electron volt is a very small unit compared to an energy unit such as a food calorie (kilocalorie). A kilocalorie is about 26 billion trillion times as large as an eV. Common multiples of eV arc McV (niillion cV), GcV (billion cV), and TcV (trillion eV). 

When water vapor condenses to liquid water, the molecules release the energy it took to separate them. A mole of gaseous water, therefore, will release 10 kilocalories of heat when condensed to liquid water at the same temperature. The amount of heat released is numerically equal to the molar heat of vaporization. 

By convention, AG is negative for a spontaneous reaction. The SI units are joule per mole G/mol). Other common units are calories per mole (cal/mol, where 1 cal = 4184J) and kilocalories per mole (kcal/mol), where 1000 cal = Ikcal. As shown next, AG of a reaction can be calculated from various types of thermodynamic data. The more negative the AG, the more lavored the reaction and the greater the amount of energy that can be released to the surroimdings. 

The amount of energy required by a human is expressed in kj d (kilojoule per day). An older unit is the kilocalorie (kcal 1 kcal = 4.187 kj). The figures given are recommended values for adults with a normal body weight. However, actual requirements are based on age, sex, body weight, and in particular on physical activity. In those involved in competitive sports, for example, requirements can increase from 12 000 to 17 000 kj d ... 

For chemical reactions and phase transformations, the energy absorbed or liberated is measured as heat. The principal unit for reporting heat is the calorie, which is defined as the energy needed to raise the temperature of 1 gram of water at l4.5° C by a single degree. The term kilocalorie refers to 1,000 calories. Another unit of energy is the joule (rhymes with school), which is equal to 0.239 calories. Conversely, a calorie is 4.184 joules. The translation of calories to joules, or kilocalories to kilojoules, is so common in chemical calculations that you should memorize the conversion factors. 

The RDA values are not requirements they are recommended daily intakes of certain essential nutrients. Based on available scientific knowledge, they are believed to be adequate for known nutritional needs for most healthy people under usual environmental stresses. The recommended allowances vary for age and sex, with extra allowances for women during pregnancy and lactation. The most commonly used RDA values (the reference male and reference female ) are those of adults 23 to 50 years of age. With the exception of energy (kilocalories), the RDA provide for individual requirement variations and prevent symptoms of clinical deficiency of 97% of the population. 

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